Volatile abundances, coma sources, and ice associations in the nucleus of comet C/2014 Q2 (Lovejoy)

High-resolution ground-based infrared spectra of bright long-period comet C/2014 Q2 Lovejoy were acquired with NIRSPEC at the Keck Observatory on two post-perihelion dates (UT 2015 February 2 and 3), when the comet was at a heliocentric distance of 1.29 au. H₂O was measured simultaneously with CO, CH₃OH, H₂CO, C₂H₆, C₂H₄, C₂H₂, HCN, and NH₃ on both dates and rotational temperatures, production rates, relative abundances, H₂O ortho-to-para ratios, and spatial distributions in the coma were determined. The first definitive detection of C₂H₄ in a comet from ground-based observations is reported. Abundances relative to H₂O for all species were found to be in the typical range compared with values for other comets in the overall population to date. There is evidence of variability in rotational temperatures and production rates on time scales that are small compared with the rotational period of the comet. Spatial distributions of volatiles in the coma suggest complex outgassing behavior. CH₃OH, HCN, C₂H₆, and CH₄ spatial distributions in the coma are consistent with direct release from associated ices in the nucleus, and are peaked in a more sunward direction compared with co-measured dust. H₂O spatial profiles are clearly distinct from CH₃OH, HCN, C₂H₆, and CH₄, but this does not rule out a close association of these ices in the nucleus if significant icy grain release in the coma influences H₂O spatial distributions. Spatial distributions for C₂H₂, H₂CO, and NH₃ suggest extended coma sources in addition to direct release from nucleus ices, providing further evidence for distinct sources and associations of these species in comets compared with other volatiles measured at infrared wavelengths. CO shows a distinct spatial distribution compared with other volatiles, consistent with jet activity from discrete nucleus ice sources.